I usually have to fish from the bank when I'm away from home for college, so I keep all my stuff in a big tackle bag. Therefore I use a lot of Plano 3600 size boxes, because 3700s are just too big. My favorite is actually the 3601, it's a shallow box. This is good for me because I have a lot of tackle for a bank fisherman, but not so much that I need deep compartments to stack 4 of the same exact bait in one slot like some guys do in their boats. So the shallow box lets me keep all of my boxes technique specific (a jerkbait box, a lipless box, a terminal box, etc) while allowing me to fit more in the bag. Three 3601 boxes are the same height as two 3600 boxes.
That being said, this might not apply if you have a boat with huge compartments where you can get away with using 3700 size boxes. I use plano because they are the most easy to come by around here and I like the prolatch.